With enhancement of the CPU performance, it has become possible to implement a virtualization technique to singly operate a plurality of operating systems (OS) in incorporated equipment or terminal in which the CPU is incorporated. In a terminal such as a portable telephone, such a system is introduced that a plurality of OSs are mounted on one device and an operation OS is changed by changing a screen. Thus, performance demanded for one terminal has been increasing. Therefore, such control has been demanded that the terminal is effectively operated with limited power while securing user operation performance of the terminal. To this demand, a plurality of operation frequencies and operation voltages of the CPU mounted on the incorporated equipment can be switched, and thus an operation speed and power consumption can be controlled.
As such related art technique, there is such technique that a first OS records an operation history and an analysis record application which is a second OS analyzes the operation history of the first OS so as to detect a sign of failure before an occurrence of failure, preliminarily execute processing of dealing with failure, and thus suppress an influence of failure. Further, there is such technique that an information gathering routine is started with event execution start of a designated task as a trigger and a processing result of the event execution and the like are recorded so as to reduce an effect to online performance and enable after offline analysis. Further, there is such technique that after a first block detects an input from a key board or the like and a second block having a memory effect is started to change a display, power supply to the first and second blocks is stopped so as to reduce power consumption.
However, in the related art techniques described above, it has been difficult to execute control satisfying both power control of a CPU of a virtualized computer system and control of processing speed. In a virtualization system, a plurality of virtual machines (VM) operate and a virtual machine monitor switches an operation of the virtual machine in response to an operation of a user or the like so as to change assignment of CPU sources to respective VMs and an operation frequency of the CPU. For example, when a user starts an operation of a portable terminal, a guest VM related to the operation and a driver VM are alternately operated in a switching manner. Accordingly, a CPU load of the system increases. However, when such configuration that the CPU load is regularly detected by using a threshold value or the like is employed, a CPU frequency is not increased unless the CPU load exceeds the threshold value. Therefore, even when a user operation is performed, execution time at a low CPU frequency is prolonged until next detection timing at which the CPU frequency is increased, causing delay of processing response with respect to the user operation.
The virtual machine monitor performs processing operated in the background other than the above-described user operation, for example, processing placing less emphasis on a response speed, such as a virus check operated in the service VM, in which power consumption of a terminal is reduced by reducing the CPU frequency depending on the CPU load. Especially, a portable terminal is driven by a battery, so that it is favorable to reduce power consumption. On the other hand, in an operation of the terminal by a user, it is preferable for the virtual machine monitor to quickly detect start of an operation and increase the CPU frequency so as to prioritize the processing speed. In the related art, it has been difficult to satisfy both of power saving of a CPU and enhancement of responsiveness of processing with respect to a user operation.